1. Field of the Invention
The subject invention relates to a sealing mechanism for a gas compressor that provides a seal about a rotary shaft to prevent fluids, such as refrigerant and lubricating oil contained in the compressor interior from leaking out to the external environment, i.e. the compressor exterior.
2. Description of the Prior Art
A typical automotive air conditioning system used in a modern automotive industry is designed to cool, dehumidify, clean, and circulate the air in a vehicle. The typical air conditioning system presents a closed, pressurized system and includes basic components such as, for example, a compressor, a condenser, a receiver/dryer or accumulator, an expansion valve or orifice tube and a plurality of additional components used in combination therewith to increase efficiency and dependability of the air conditioning system.
The compressor is the heart of the automotive air conditioning system and is designed to separate high-pressure and low-pressure sides of the air conditioning system and includes outlet and inlet portions. The primary purpose of the compressor is to draw the low-pressure and low-temperature vapor from the evaporator and compress this vapor into high-temperature, high-pressure vapor. The secondary purpose of the compressor is to circulate or pump a refrigerant through the air conditioning system under the different pressures required for proper operation of the air conditioning system. The compressor is located in an engine compartment and is driven by the engine's crankshaft via a drive belt.
The modern automotive industry includes numerous types of compressors. The types include a piston compressor, a rotary vane compressor, and a scroll-type compressor. The piston compressor includes pistons arranged in an in-line, axial, or radial designs. The pistons are engaged in cylinders, respectively, and designed to have an intake stroke and a compression stroke for each cylinder. The common variation of the piston type compressor is a variable displacement compressor, wherein the pistons are connected to a swash plate.
Conventional knowledge that is backed by test data supports the finding that refrigerant oil reduces refrigerant emissions from various components of the compressor, such as sealing lip portions of a shaft seal and O-rings, in which the refrigerant oil is present. Specifically, these components, formed from polymer, exhibit significant reduction in refrigerant permeation (or leakage) rates when these components are coated with a film of lubricant. In a pressure vessel that contains microscopic leak paths, refrigerant, backed by pressure potential, eventually displaces oil molecules in these microscopic leak paths. Consequently, the pressure vessel, wherein these leak passages are contained, develops a leak rate that is substantially higher than the leak rate when such passages are blocked, i.e. coated with the lubricant. Refrigerant leakage from the shaft seal of the compressor has long been identified as a source of leakage from refrigeration systems that can lead to increased frequency of system repair as well as contributing to atmospheric emissions of gases with a potential to contribute negatively to global climate change (greenhouse gas effect).
The art is replete with various designs of the variable displacement compressors disclosed in U.S. Pat. No. 3,945,765 to Toyoda et al.; U.S. Pat. No. 4,095,921 to Hiraga et al.; U.S. Pat. No. 4,428,718 to Skinner; U.S. Pat. No. 4,444,549 to Takahashi et al.; U.S. Pat. No. 4,960,366 to Higuchi; U.S. Pat. No. 5,056,416 to Ota et al.; U.S. Pat. No. 5,255,569 to Terauchi et al.; U.S. Pat. No. 6,416,297 to Kawaguchi et al; U.S. Pat. No. 6,564,695 to Herder et al; and U.S. Pat. No. 6,589,022 to Yokomachi et al.
The U.S. Pat. No. 6,589,022 to Yokomachi et al. teaches a compressor having a cooling structure to effectively cool a sealing device having at least first and second sealing lip portions interposed in an opening defined between a housing of the compressor and a drive shaft. A passage is exposed to a hole fluidly communicated with the opening for circulating a lubricant into the opening to lubricate exterior of only one of the sealing lip portions of the sealing device.
There is a need in the area of the compressor manufacturing industry for an improved lubrication system for lubricating a sealing device wherein the lubrication system is adaptable to maintain a reservoir of grease to ensure that components of the sealing device have adequate lubrication or grease to ensure a good sealing environment and to reduce refrigerant emission.